Selective conductive interstitial thermal therapy device

ABSTRACT

An apparatus and method for thermally destroying tumors. A tip has a plurality of deployable thermal conductive elements whose temperatures are individually controllable. This allows the shape of the thermal field to be controlled and for specific areas to be protected from excessive heat by cooling those specific areas while ablating other areas. In another embodiment, the deployable thermal conductive elements are individually deployable to various lengths to further aid in shaping the thermal field. The temperatures and the shape of the thermal field may be monitored and controlled by a data processing device, such as a microprocessor. Further selectivity in defining the area of tissue to be treated may be achieved by introducing into the tissue thermal additives that alter the thermal properties of the tissue.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of pending U.S. patentapplication Ser. No. 11/028,157, filed Jan. 3, 2005, which is acontinuation of U.S. patent application Ser. No. 10/336,973 filed Jan.6, 2003, now U.S. Pat. No. 6,872,203, which is a continuation-in-part ofU.S. patent application Ser. No. 10/228,482 filed Aug. 27, 2002, nowU.S. Pat. No. 6,780,177, all of which are incorporated herein byreference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to methods and devices for treating bodytissues such as tumors or lesions with thermal energy, and inparticular, to such methods and devices that deploy thermally conductiveelements to treat a predetermined shape of tissue.

2. Brief Description of the Related Art

Within the last ten years, interstitial thermal therapy of tumors hasbecome an accepted method for treating cancerous tumors. These minimallyinvasive therapeutic procedures are used to kill cancer tumors withoutdamaging healthy tissues surrounding it. Increasing the temperature ofthe tumor above a threshold level of about 70-130 C will cause tumordeath. Interstitial thermal devices for thermal tissue ablationincluding radio frequency ablation (RFA), microwave and laser basedtechnologies have been developed and have received 510K FDA clearance.All of these techniques use radiation to transfer the energy to thetumor, and therefore the heat in the tumor is generated indirectlythrough local energy absorption sites (e.g., blood in the case of alaser or fat in the case of RFA) could result in a non-homogenousheating of the tumor. The consequences of a non-uniform heating of thetumor could include incomplete death of the tumor and/or skin burns andinjury of healthy tissues or organs. Incomplete tumor death will resultin recurrence of multiple small tumors in the treated area.

Moreover, as most of the heat is transfer by radiation (in laser, RFAand microwave), it is very difficult to calculate the temperaturedistribution without precisely knowing the fine microstructure (down tothe cell level) that cannot be predetermined with a non-invasive method.In addition the temperature measurements are also challenging; in thesecases, since the probes could be directly heated by the energy sourcesand will show it's own temperature rather than that of the tissue. Forexample, in laser or RFA thermocouples may get hot from the source muchquicker than tissue (as they absorb RF and laser energy more thantissue) and will show temperatures that are higher than the actualtemperature in the lesion. That could result in insufficient heating andif the operator increases the amount of energy delivered to the tumor,an overheating may occur which will result in burning. Anotherlimitation of RFA is that it is not MRI-compatible.

The limitations of the prior art are overcome by the present inventionas described below.

BRIEF SUMMARY OF THE INVENTION

The present invention is an alternative to Laser Interstitial ThermalTherapy (LLIT) and RFA, which is used to destroy tumors or lesionsthrough the absorption of radiation by tissue. However, as discussedabove, in the LLIT and RFA processes, the temperature cannot bepredicted or easily controlled due to the varying light and RF energyabsorption properties of different types of tissue. In addition, RFAwill interfere with implants (such as pacemakers) and the patient withsuch implants cannot be treated with RFA.

The present invention also destroys tumors thermally, but the heat isgenerated directly by heat, such as by electrical resistance heating,conducted to the tissue rather than through the absorption ofnon-ionized radiation by the tissue. A process of the present inventionmay involve digital imaging (x-ray, ultrasound) and/or computerizedscanning (CAT, CT, PET, or MRI) to mathematically determine the locationand shape of the tumor. The information derived from the scan allows astereotactic frame or other technique such as ultrasound to be used toposition a probe within the tumor.

In one embodiment, the probe comprises a thermally conductive tipcontaining an electrical resistance heating element. The thermallyconductive tip is mounted on the end of a fiber which is separated fromthe tip by a heat sink to avoid thermal conduction down the fiber. Thefiber contains the electrical power leads and other electrical leadsconnecting to monitoring devices associated with the tip. The tip iscoated with a thin biocompatible coating, such as diamond-like coating,ceramic, polymers and the like, to avoid coagulated tissue sticking tothe tip.

The area of tissue treated by the tip is determined by the addition ofone or more thin, thermal conductive elements, which may be formed ofshape memory material, such as nitinol. The shape memory elements aredesirably in the form of thin wires or pins which are folded against thetip at lower temperatures and which deploy at selected highertemperatures. The shape memory elements may be deployed in multiplestages at succesively higher temperatures so that succesive layers ofthe tumor are exposed to specific temperatures during treatment.Coagulating the tumor in successive layers is desirable to avoidhemoraging. By selecting the number, size and placement of the shapememory elements, tumors of varying sizes and shapes may be treated in apredictable, controllable fashion.

In order to control the process, the tip may also be provided with aminiature thermocouple or the like to provide temperature feedbackinformation to control the temperature of the tip. Through knowledge ofthe shape and location of the tumor obtained from computerized imaging,the design of the tip and thermal conductive elements, and thetemperature feedback information, information can be presented to theoperator showing the specific progress of the treatment of a tumor andallowing predictable control of the process.

In alternative embodiments, deployable pivoted razorblades rather thanthin wires are employed to conduct the thermal energy to the tumor. Therazorblades are deployed mechanically rather than being deployed due totemperature dependent shape memory effects. In one embodiment, a linearactuator, comprising a threaded shaft operated by a motor, deploys therazorblade thermal conductive elements. In another embodiment, a nitinolspring is heated so as to extend and deploy the razorblade elements.

In some embodiments, a pyrolytic graphite element may be used to providethe heat source. Pyrolytic graphite has unique thermal properties inthat it acts as a resistor axially but is conductive radially.

In a further embodiment, the deployable razorblades are deployedmechanically by a spring-biased copper conductor that serves a dualfunction--as a plunger to push deploying arms on the razorblades andalso as a conductor for the power supply for the pyrolytic graphiteheater element. The plunger is housed in a shaft which is coated with anelectrically conductive material, for example, gold, to act as the powerreturn or ground so as to complete the electrical circuit supplyingpower to the heater-element. When the plunger moves forwardly to pushthe arms on the razorblades, it may also extend a needle which helps tohold the probe in place when the razorblades deploy.

The deployable razorblades may be deployed in stages to treat the tumorlayer by layer. The deployment may be triggered at specifiedtemperatures as measured by temperature feedback elements in the probetip.

The present invention uses thermal conduction, as opposed to radiationabsorption, to heat the tumor/lesion volume. Since the thermalproperties of tissue are relatively homogenous, the results can bepredicted. The shape of the probe tip in the form of the deployablethermal conductive elements may be altered during treatment. Thecombination of shape and activation temperature can be predetermined forany specific tumor/lesion geometry. This offers the followingadvantages: highly predictable temperature distribution; larger areascan be effectively treated, in a controlled manner, since the heat isdissipated primarily by conduction; localized carbonization will notresult in tunneling and the process is safer than LLIT or RFA; themaximum temperature in the treatment zone will never exceed thetemperature at the tip of the probe, and therefore, one can easilycontrol the maximum temperature within the tumor/lesion and adjacenttissues; and temperature may be actively controlled via closed loopfeedback system, where the maximum temperatures are measured during theprocess by placing miniature thermocouples at the end of the thermalprobe.

In an alternative embodiment, the tip is provided with a plurality ofdeployable elements whose temperatures are individually controllable toprovide heat to the elements and surrounding tissue. This allows theshape of the thermal field to be controlled and for specific areas to beprotected from excessive heat by cooling those specific areas whileablating other areas. Treatment areas can be targeted more effectivelyand particularly sensitive areas can be protected from ablation. Thus,it is possible to ablate targeted areas of tissue near the chest wall,in the head and neck, liver, pancreas and other regions where portionsof the tissue require ablation, but nearby portions must be protectedfrom ablation to avoid life threatening injury. The deployable elementsmay be heated or cooled by any of various techniques known to thoseskilled in the art. For example, heat may be supplied from a miniatureresistance heating coil in each deployable element. Cooling may beaccomplished by Peltier effect devices. Heating and/or cooling may beapplied by introducing heated or chilled fluid, either liquid such aswater or gas such as argon, to a hollow space within the deployablethermal conductive elements.

The temperature of the thermal conductive elements may be monitored bythermal sensors at the ends of the elements. The thermal sensors may beminiature thermocouples located within the end of each element. Thetemperatures may be monitored and controlled by a data processingdevice, such as a microprocessor.

In a further alternative embodiment, the tip is provided with aplurality of deployable elements that are individually deployable tovarious shapes. The deployable elements remain retracted in the tipduring insertion into the tissue to be treated. The tip may be heated byjoule heating using a miniature heating coil and/or the individualelements may be separately heated. Each element is individuallyconnected to means for deploying the elements. The deploying means may adirect mechanical connection from the elements to an external mechanicalcontrol or the deploying means may be associated with each individualdeployable element. Other techniques to deploy the elements to aspecified length would be known to those skilled in the art. Thesetechnique could include electromechanical or pneumatic means. Othertechniques could include the application of temperature to induce ashape change in bimetallic elements. Over- or under-treatment of thetissue may be avoided by deploying the deployable elements toindividually predetermined lengths to generate a thermal field thatapproximates the shape of the spatial volume of the tissue to betreated.

Each deployable element may include its individual temperature and/orshape controller in an associated modular package. The tip may beconnected by a hollow fiber to external control devices, such as amicroprocessor, mechanical actuator, heating and/or cooling fluidsupply, thermal additive supply, and electrical power. Each modularpackage may be connected via control lines through the hollow fiber tothe respective external control devices.

Any number of deployable elements could be used depending upon theapplication. Although the present invention is not limited thereto, ithas been found that eight (8) deployable elements allow the creation ofa thermal field that can conform to various shapes of tissues to betreated, for example, spherical, ellipsoidal or oblong. Various sizesand shapes of the tip and the deployable elements may be used to fitvarious shapes of tissue to be treated. The tip, the deployable elementsand the associated temperature and/or shape controllers may bereplaceable and disposable.

Further selectivity in defining the area of tissue to be treated may beachieved by introducing into the tissue thermal additives that alter thethermal properties, such as thermal diffusivity, specific heat capacity,density or thermal conductivity, of the tissue. Such additives are knownto those skilled in the art and may include carbon particles (from 1 nmto 5000 μm) and metal particles including gold nano-particles. Variouschemicals are known in the art that bind selectively to tumor cells orthat otherwise accumulate in tumors and that can alter the thermalproperties of the tumor. It is also known that glucose will increase thethermal conductivity of a tumor into which it is introduced.

The thermal additives may be introduced into the tissue to be treated byvarious means, for example, by intralesional injection or by intravenousinjection. Further, the deployable elements may be employed to spraysuch additives onto the tissue during or before treatment. A hollow ductin the deployable element may be connected through control lines in thehollow fiber to a source of the additive. The additive is than sprayedfrom one or more ports opening into the hollow duct.

These and other features, objects and advantages of the presentinvention will become better understood from a consideration of thefollowing detailed description of the preferred embodiments and appendedclaims in conjunction with the drawings as described following.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIGS. 1A, 1B and 2 are views of an embodiment of the present inventionin which the deployable thermal conductive elements are shape memorywires. FIG. 1A is a perspective view showing the first stage deploymentof the shape memory wires. FIG. 1B shows the second stage deployed. FIG.2 is a sectional view of the device of FIGS. 1A and 1B along the lines2-2 of FIGS. 1A and 1B with the shape memory wires in the non-deployedconfiguration.

FIGS. 3-5 are views of an alternative embodiment of the presentinvention in which the deployable thermal conductive elements arepivoted razorblades deployed by a linear actuator. FIG. 3 is aperspective view of the present invention in which the pivotedrazorblades are shown by broken lines in the deployed configuration.FIG. 4 is a sectional view along the line 3-3 of FIG. 3. FIG. 5 is asectional view along the line 5-5 of FIG. 3.

FIG. 6 is a sectional view of a further alternative embodiment of thepresent invention in which the deployable thermal conductive elementsare pivoted razorblades deployed by a nitinol muscle wire.

FIG. 7 is a sectional view of a further alternative embodiment of thepresent invention in which the deployable thermal conductive elementsare pivoted razorblades deployed by a plunger. The activation of theplunger also deploys a needle through the forward end of the tip.

FIG. 8 is a block diagram of a method of the present invention.

FIGS. 9 and 10 are views of an embodiment of the present invention inwhich the deployable thermal conductive elements are shape memory wiresin the form of coils. FIG. 9 is a perspective view showing thedeployment of the shape memory wires. FIG. 10 is a sectional view of thedevice of FIG. 9 along the lines 10-10 with the shape memory wires inthe non-deployed configuration.

FIGS. 11A and 11B are sectional views of an alternative embodiment ofthe embodiment of FIG. 7 wherein the deployed razorblades are springbiased to aid in retraction of the razorblades from the deployedposition. FIG. 11A is an embodiment in which the biasing spring islocated to the proximal side of the probe and FIG. 11B is an embodimentin which the biasing spring is located to the distal side of the probe.

FIG. 12 is a schematic view of an embodiment of the invention in whichthe tip of the device is a metal tip heated by a remote laser through awaveguide.

FIG. 13 is a schematic diagram of a cross section of an embodiment of aprobe, including a tip, a plurality of deployable thermal conductiveelements, and associated temperature and/or length controllers.

FIG. 14 is a schematic diagram of an individual deployable thermalconductive element and its associated temperature and/or lengthcontroller with connections via control lines to external controllers.

FIGS. 15A and 15B illustrate a thermal field generate by a probe. FIG.15A illustrates the situation where some of the thermal conductiveelement are heated and some cooled. FIG. 15B illustrates the effect onthe thermal field of extending the thermal conductive elements tovarious lengths.

FIG. 16 is a partial cross section of the end of a thermal conductiveelement showing a miniature thermocouple in the end.

FIG. 17 is a partial cross section of the end of a thermal conductiveelement showing a hollow duct and ports for spraying thermal additives.

DETAILED DESCRIPTION OF THE INVENTION

With reference to FIGS. 1A-12, the preferred embodiments of the presentinvention may be described as follows.

The present invention is a miniature thermal apparatus for thecontrolled destruction of malignant and benign tumors/lesions andabnormal or excess tissue. As used herein, the terms tumors and lesionsmay be used interchangeably to indicate tissue to be thermally treatedby the device and method of the present invention. The present inventioncomprises a tip 10 mounted onto a fiber 11 that can be inserted througha catheter that has been accurately placed within the tumor/lesion. Thetumor/lesion is destroyed via heat generation originating from thespecifically designed tip 10 that matches the tumor/lesion geometry. Thetip 10 comprises a plurality of deployable thermal conductive elementsthat may be customized by the number, size and arrangement to bedeployable into a geometry that matches the geometry of the tumor/lesionto be thermally treated. The temperature distribution around the tip 10,within the tumor/lesion and in the adjacent tissue may be predicted bymathematical models of the heat transfer equations. Software may beemployed in conjunction with the mathematical models of the heattransfer to provide (1) process monitoring and control, (2) custom probedesign, and (3) process simulation. Additionally, using this predictiveability, the process may be monitored and controlled with a closed loopfeedback system utilizing sensors in the tip 10. The geometry of the tip10 may be changed as a function of temperature to increase the volume ofirreversibly damaged tissue in the tumor/lesion.

As shown in FIG. 8, a process of the present invention involves the stepof computerized scanning (CAT, CT, PET, or MRI) to mathematicallydetermine the location and shape of the tumor 20. The informationderived from the scan allows the geometry of the tip to be customized totreat the specific shape of the tumor 21 and also allows a stereotacticframe to be used to position the probe within the tumor 22. Ultrasoundor the like may be also used to position the probe. The probe isinserted into the tumor 23, and the heating element is activated to apredetermined temperature to treat the tumor 24. Alternatively, thetemperature may be increased in a stepwise fashion to treat the tumor inlayers 25. Finally, the probe is cooled and withdrawn from the treatedtumor 26. As an adjunct to the treatment process, the coagulation of thetumor may be enhanced by the use of a drug effective in reducingbleeding from vascular damage, such as NovoSeven (recombinant factorVIIa) or other coagulant enhancement drug such as Aminocaproic acid(Amicar). NovoSeven is used to stop bleeding in various surgicalprocedures. The drug is delivered systemically but only works in regionsof the body in which vascular damage has taken place. In the procedureof the present invention, the drug would be administered approximatelyten minutes prior to the procedure. Thereafter, the apparatus of thepresent invention is introduced into the tumor. Once the temperature ofthe tissue has increased to the point that the endothelial cells in theblood vessels are damaged, coagulation is initiated by NovoSeven in theareas of the damaged vessels. The process aids in heat transfer and mayaid in the destruction of the tumor by nutrient deprivation. Anancillary advantage to using NovoSeven is that it will decrease the riskof bleeding along the track of the apparatus. The drug is metabolized inabout two hours.

The thermally conductive tip 10 contains an electrical resistanceheating element 13. The thermally conductive tip 10 is mounted on theend of fiber 11 which is separated from the tip 10 by a heat sink 12 toavoid thermal conduction down the fiber 11. The fiber 11 contains theelectrical power leads 14 and may also contain other electrical leadsconnecting to monitoring devices associated with the tip 10. The tip 10is coated with a thin biocompatible coating 15 to avoid coagulatedtissue sticking to the tip 10. The thin biocompatible coating 15 may bediamond-like coatings, ceramic, polymers and the like.

The area of tissue treated by the tip 10 can be adjusted by the additionof one or more deployable, thermal conductive elements. The deployableelements may be shape memory elements 16 made of shape memory materials,such as nitinol. The shape memory elements 16 are desirably in the formof thin wires or pins which are folded against the tip 10 at lowertemperatures as shown in FIG. 2 and which deploy at selected highertemperatures. The shape memory elements 16 may be deployed in multiplestages at succesively higher temperatures so that succesive layers ofthe tumor are exposed to specific temperatures during treatment. Forexample, a set of short shape memory elements 17 may be deployed at afirst temperature and a set of longer shape memory elements 18 may bedeployed at a higher second temperature. Coagulating the tumor insuccessive layers is desirable to avoid hemoraging. By selecting thenumber, size and placement of the shape memory elements 16, tumors ofvarying sizes and shapes may be treated in a predictable, controllablefashion.

In order to control the process, the tip 10 may also be provided with aminiature thermocouple to provide temperature feedback information tocontrol the temperature of the tip 10. Through knowledge of the shapeand location of the tumor obtained from computerized imaging, the designof the tip 10 and shape memory elements 16, and the temperature feedbackinformation, information can be presented to the operator showing thespecific progress of the treatment of a tumor and allowing predictablecontrol of the process.

As shown in FIGS. 9 and 10, an alternative design of shape memoryelements 30 employs shape memory material, such as nitinol, in the formof coils which expand to a deployed configuration as shown in FIG. 9from a non-deployed configuration as shown in FIG. 10.

Alternative embodiments as shown in FIGS. 3-7 use deployable pivotedrazorblades 30 rather than thin shape memory wires as the thermalconductive elements to conduct the thermal energy to the tumor.Desirably, the pivoted razorblades 30 may be made of biocompatiblematerials, such as composite materials including aluminum siliconcarbide, titanium boride and the like. The pivoted razorblades 30 may bedeployed mechanically rather than being deployed by a nitinol shapememory wire element. In one embodiment shown in FIG. 4, a linearactuator, comprising a threaded shaft 31 operated by a motor (notshown), deploys the razorblade 30. In another embodiment shown in FIG.6, a nitinol spring 32 is heated so as to extend and deploy therazorblade elements 30. In both embodiments, a pyrolytic graphiteelement 33 may be used to provide the heat source. Pyrolytic graphitehas unique thermal properties in that it acts as a resistor axially butis conductive radially.

In a further embodiment shown in FIG. 7, the deployable razorblades 30are deployed mechanically by a spring-biased copper conductor thatserves as a plunger 34 to push deploying arms 35 on the razorblades 30.The plunger 34 also acts as a conductor for the power supply for thepyrolytic graphite heater element 33. The copper conductor is housed ina shaft 36 which is coated with an electrically conductive material suchas gold to act as the power return or ground so as to complete theelectrical circuit supplying power to the heater element 33. When thecopper conductor plunger 34 moves forwardly to push the arms 35 on therazorblades 30, it may also extend a needle 36 which helps to hold theprobe in place when the razorblades 30 deploy.

FIGS. 11A and 11B are sectional views of an alternative embodiment ofthe embodiment of FIG. 7 wherein the deployed razorblades 30 are biasedby spring 40, 42 to aid in retraction of the razorblades 30 from thedeployed position. FIG. 11A is an embodiment in which biasing spring 40is located to the proximal side of tip 10. Spring 40 is fixed at one endin a bore 43 and at the other end to deploying arm 35. As razorblade 30is extended, spring 40 also extends and exerts a force tending toretract razorblade 30. FIG. 11B is an embodiment in which the biasingspring 42 is located to the distal side of tip 10. Spring 42 bearsagainst pin 41 which in turn bears against deploying arm 35. Asrazorblade 30 is deployed, spring 42 is compressed and thereby exerts aforce tending to retract razorblade 30. Biasing springs 40, 42 may alsobe used in the embodiments of FIGS. 4 and 6 as well as FIG. 7.

The device may require increasing the minimum size of the catheter sincethe tip 10 of the probe may be larger than a standard laser tip.

This limitation is not serious, however. Although the size of thethermal tip 10 is expected to be larger than a standard laser tip, themaximum size could be limited to 1.6-5 mm in diameter, which is stillacceptable for interstitial procedures. Also, as shown in FIG. 12, thesize of the tip 10 could be reduced to LITT size, by using a laser 50 asan energy source to heat up a metal tip 10.

When using a laser 50 as an energy source, the laser 50 is remotelylocated from the metal tip 10 and the laser radiation is transmittedthrough a wave guide fiber 51 to the metal tip 10. The metal tip 10 isdesirably stainless steel. The metal tip 10 absorbs the laser radiationand is heated thereby to a high temperature, e.g., 150° C. The heat ofthe heated metal tip 10 is dissipated to the surrounding tissue throughconduction, thereby causing blood coagulation and tissue necrosis aroundthe metal tip 10 in a well defined region. In order to limit the heatflow from the metal tip 10 to the wave guide fiber 51, a heat conductivebarrier 52 in the form of insulation or a heat sink may be placedbetween the metal tip 10 and the wave guide fiber 51. Further, the waveguide fiber 51 may have an insulating jacket 53. The wave guide fiber 51may also be cooled by cool air flowing through the wave guide fiber 51.A portion of the wave guide fiber 51 adjacent to the metal tip 10 may bein the form of a tube 54 through which the cool air flows. The tube 54may be formed from a metal, such as copper, a composite material or aceramic material.

The laser 50 is desirably a CO₂ laser. Although there is low absorption(around 9%) of CO₂ laser radiation by stainless steel, the amount ofenergy required to heat stainless steel is low due to the low heatcapacity of stainless steel (0.46 Jgr⁻¹C⁻¹) compared to blood (3.6Jgr⁻¹C⁻¹). Therefore, a stainless steel metal tip 10 of 1 gram could beheated to high temperatures of up to 300-500° C. by a 50 Watt CO₂ laser.

To avoid tissue sticking, the metal tip 10 is desirably coated with athin layer, e.g., 5 μm, of biocompatible ceramic, such as alumina ortitanium nitride, or a biocompatible polymer, such as Teflon®. A ceramiccoating may be applied by physical vapor deposition, a standard processin the industry.

Since the heat of the metal tip 10 is dissipated by conduction, thetemperature profile can be calculated using known finite difference orfinite element methods. Since the thermal properties of all humantissues are similar, accurate temperatures predictions are possible.Since the critical temperatures are not a strong function of time, theirreversible thermal damage of tissues can be controlled through theheating time. To limit necrosis of tissues to a well defined region, thesize of the metal tip 10 can be minimized. Deployable thermallyconductive elements, as described heretofore, may be added to the metaltip 10 to determine the shape of the thermally treated tissue. Suchdeployable thermal elements may be deployed in stages.

With reference to FIGS. 13-17, an alternative embodiment of the presentinvention is described. In this alternative embodiment, the tip 60 isprovided with a plurality of deployable elements 61 with temperatureproviding means for providing for providing an individually controllabletemperature to said each deployable element and its surrounding tissue.This allows the shape of the thermal field 66 to be controlled and forspecific areas to be protected from excessive heat by cooling thosespecific areas while ablating other areas. For example, as shown in FIG.15A, elements 61 are heated and element 80 is cooled, producing thethermal field 66. Treatment areas can be targeted more effectively andparticularly sensitive areas can be protected from ablation. Thus, it ispossible to ablate targeted areas of tissue near the chest wall, in thehead and neck, liver, pancreas and other regions where portions of thetissue require ablation, but nearby portions must be protected fromablation to avoid life threatening injury. The deployable elements maybe heated or cooled by any of various techniques known to those skilledin the art. For example, heat may be supplied from a miniatureresistance heating coil in each deployable element. Cooling or heatingmay be supplied the action of an electromagnetic field, such as Peltiereffect devices. Heating and/or cooling may be applied by introducingheated or chilled fluid, either liquid such as water or gas such asargon, to a hollow space (not shown) within the deployable elements 61.Fluids, solids, gases or mixtures of the same at temperatures below themaximum temperature of the probe may be used to cool the deployableelements 61 and their surroundings. Cooling may also be provided by theinteraction of an electromagnetic field with a gas, liquid, solid or amixture of any of the preceding. Other cooling means could include theuse of chemical or biological endothermic reactions induced by mixingone or more solids and/or one or-more liquids. In addition, a separatecooled probe may be provided such that its temperature in combinationwith selected temperatures for each deployable element provide thedesired thermal field. All means for cooling the deployable elements 61are encompassed herein by the term “heat sink.” The thermal treatment ofthe tissue may occur by the thermal conduction of heat from theindividual elements or may be from high temperature solids, liquids,gases or mixtures of the preceding injected from the deployable elementsor the tip into the target tissue. Injection may be accomplished asdescribed below with respect to the injection of additives to alter thethermal properties of the tissue.

The temperature of the deployable elements 61 may be monitored bythermal sensors at the ends of the elements. The thermal sensors may beminiature thermocouples 62 located within the end of each element 61.The temperatures may be monitored and controlled by a data processingdevice, such as a microprocessor 63.

In a further alternative embodiment, the tip 60 is provided with aplurality of deployable elements 61 that are individually deployable tovarious shapes. The deployable elements remain retracted in the tipduring insertion into the tissue to be treated. The tip 60 may be heatedby joule heating using a miniature heating coil and/or the individualelements may be heated separately. Each element 61 is individuallyconnected to means for deploying the elements. The deploying means may adirect mechanical connection from the thermal conductive elements 61 toan external mechanical control 64 or the deploying means may beassociated with each individual deployable element 61 as describedbelow. Other techniques to deploy the elements 61 to a specified shapewould be known to those skilled in the art. These techniques couldinclude electromechanical or pneumatic means. Other techniques couldinclude the application of temperature to induce a shape change inbimetallic elements. Over- or under-treatment of the tissue may beavoided by deploying the deployable conductive elements 61 toindividually controllable shapes to generate a thermal field 70 thatapproximates the shape of the spatial volume of the tissue to treated.As shown in the example of FIG. 15B, the thermal field 70 is generatedby elements 61 having the same extended shape and element 81 having ashorter extended shape. The deployable elements themselves may comprisesub-elements or materials that deploy to form various shapes.

Each deployable element 61 may include its individual temperature and/orshape controller in a modular package 65. The tip 60 may be connected bya hollow fiber 66 to external control devices, such as a microprocessor63, mechanical actuator 64, heating and/or cooling fluid supply 67,thermal additive supply 68, and electrical power 69. Each modularpackage 65 may be connected via control lines 71 through the hollowfiber 66 to the respective external control devices 63, 64, 67, 68, 69.

Any number of deployable elements 61 could be used depending upon theapplication. Although the present invention is not limited thereto, ithas been found that eight (8) deployable elements 61 allow the creationof thermal fields 66, 70 that can conform to various shapes of tissue tobe treated, for example, spherical, ellipsoidal or oblong. Various sizesand shapes of the tip 60 and the deployable elements 61 as describedherein may be used to fit various shapes of tissue to be treated. Thetip 60 and the deployable elements 61 may be replaceable and disposable.

Further selectivity in defining the area of tissue to be treated may beachieved by introducing into the tissue thermal additives that alter thethermal properties, such as thermal diffusivity, specific heat capacity,density or thermal conductivity, of the tissue. Such additives are knownto those skilled in the art and may include carbon particles (1 nm to5000 μm) and metal particles including gold nano-particles. Variouschemicals are known in the art that bind selectively to tumor cells orthat otherwise accumulate in tumors and that can alter the thermalproperties of the tumor. It is also known that glucose will increase thethermal conductivity of a tumor into which it is introduced. Anyparticles, solutions containing particles, metals, ceramics, composites,polymers, organic and inorganic chemicals, solids, liquids, gases andmixtures of the preceding that alter the thermal properties of thetissue (either normal or abnormal tissue) are considered to be additivesas encompassed within the scope of the present invention.

The thermal additives may be introduced to the tissue to be treated byvarious means, for example, by intralesional injection or by intravenousinjection. More generally, the present invention encompasses theintroduction of additives by an external applicator. The thermaladditives may also be introduced systemically to change or affect theproperties of the target tissue and boundary in order to make the targettissue more susceptible to thermal treatment. Further, the deployableelements may be employed to spray such additives onto the tissue duringor before treatment. A hollow duct 72 in the deployable element 61 maybe connected through control lines 71 in the hollow fiber 66 to a sourceof the additive 68. The additive is than sprayed from one or more ports73 opening into the hollow duct 72.

The present invention has been described with reference to certainpreferred and alternative embodiments that are intended to be exemplaryonly and not limiting to the full scope of the present invention as setforth in the appended claims.

1. An apparatus for the thermal treatment of tissues, comprising: a tip;a plurality of deployable elements operatively connected to said tip;and temperature providing means associated with each element of saidplurality of deployable elements for providing an individuallycontrollable temperature from said each element to said element'srespective surrounding tissue.
 2. The apparatus of claim 1, furthercomprising a temperature sensor associated with said each element. 3.The apparatus of claim 1, where said temperature providing means furthercomprises a heat sink.
 4. The apparatus of claim 1, wherein saidtemperature providing means comprises an electromagnetic field.
 5. Theapparatus of claim 3, wherein said heat sink comprises a solid, fluid,gas or mixture of any of the preceding at a temperature below themaximum temperature of the apparatus.
 6. The apparatus of claim 1,wherein said temperature providing means comprises means for injectinghigh temperature solids, liquids, gases or mixtures of the precedinginto said respective surrounding tissue from said deployable elements.7. The apparatus of claim 1, wherein said deployable elements comprisemeans for applying additives that change the thermal properties of thetissue.
 8. The apparatus of claim 7, wherein said additives compriseparticles, solutions containing particles, metals, ceramics, composites,polymers, organic and inorganic chemicals, and mixtures of any of thepreceding.
 9. The apparatus of claim 1, further comprising deploymentproviding means associated with each element of said plurality ofdeployable elements for deploying said each element to an individuallycontrollable shape.
 10. The apparatus of claim 9, wherein saidtemperature providing means further comprises a temperature sensorassociated with said each element.
 11. The apparatus of claim 9, wheresaid temperature providing means further comprises a heat sink.
 12. Theapparatus of claim 11, wherein said means for cooling comprises anelectromagnetic field.
 13. The apparatus of claim 11, wherein said meansfor cooling comprises a solid, fluid, gas or mixture of any of thepreceding at a temperature below the maximum temperature of theapparatus.
 14. The apparatus of claim 9, wherein said temperatureproviding means comprises means for injecting high temperature solids,liquids, gases or mixtures of the preceding into said respectivesurrounding tissue from said deployable elements.
 15. The apparatus ofclaim 9, wherein said deployable elements comprise means for applyingadditives that change the thermal properties of the tissue.
 16. Theapparatus or claim 15, wherein said additives comprise particles,solutions containing particles, metals, ceramics, composites, polymers,organic and inorganic chemicals, and mixtures of any of the preceding.17. A method for the thermal treatment of tissue, comprising the stepsof (a) determining a spatial shape of a volume of tissue to be treated;(b) providing a tip having a plurality of deployable elements comprisingtemperature providing means associated with each element of saidplurality of deployable thermal conductive elements for providing anindividually controllable temperature from each said element to saidelement's respective surrounding tissue; (c) selecting a temperature foreach element whereby a thermal field is generated having a shapeselected to treat the spatial shape of the volume of tissue; (c)positioning the tip into the volume of tissue to be treated; (d)generating the temperature selected for each element; (f) maintainingthe tip in the tissue for a sufficient period of time to treat thetissue; and (g) removing the tip from the tissue.
 18. The method ofclaim 17, wherein said tip further comprises deployment providing meansassociated with each element for deploying each element to anindividually predetermined shape, further comprising the steps, prior-tostep (f), of: selecting a shape for each element whereby in combinationwith the selected temperatures of step (c) a thermal field is generatedhaving a shape selected to treat the spatial shape of the volume oftissue; and deploying each element to the selected shape.
 19. The methodof claim 17, further comprising the step, prior to step (f), of applyingadditives to the tissue.
 20. The method of claim 19 wherein saidadditives comprise particles, solutions containing particles, metals,ceramics, composites, polymers, organic and inorganic chemicals, andmixtures of any of the preceding.
 21. The method of claim 19, whereinsaid step of applying additives comprises introducing said additives byan external applicator.
 22. The method of claim 19, wherein said step ofapplying additives comprises introducing said additives systemically.23. The method of claim 18, further comprising the step, prior to step(f), of applying additives to the tissue.
 24. The method of claim 23wherein said additives comprise particles, solutions containingparticles, metals, ceramics, composites, polymers, organic and inorganicchemicals, and mixtures of any of the preceding.
 25. The method of claim23, wherein said step of applying additives comprises introducing saidadditives by an external applicator.
 26. The method of claim 23, whereinsaid step of applying additives comprises introducing said additivessystemically.
 27. The method of claim 17, wherein step (c) furthercomprises providing a separate cooled probe having a temperatureselected to provide, in combination with said selected temperature foreach said element, said thermal field.